This is the stuff of urban legend. Unlike a drive-up tellers vacuum propelled cash can, this train is not propelled by any air pressure differential. It simply coasts in a drag-free airless tube after an initial acceleration. For bearings, think mag lev without propulsion.
First, got to build the tube to withstand 4kg/cm2 pressure (at about 100 feet deep) and be rigid enough to withstand wave action flexing so as to maintain tight mag-lev tolerances. Got to keep the tube in place - either with multi propellors with gps feedback or bouys in opposition with deep sea anchors.
Next, got to evacuate some 7.7 million cu meters of air. Next, capsule has to provide fresh air at atmosphere pressure for passenger comfort. Got a problem? Need escape hatches periodically which must have vacuum locks to admit you to 100 ft sea depth for prompt medical attention.
And last, this thing has to have automatic terrorist detection and annihilation. And better add an iceberg detector - one Titanic is enough.
I'm recommending everyone purchase a share in this, just to get the bridge that surely must come with it.

This is the stuff of urban legend. Unlike a drive-up tellers vacuum propelled cash can, this train is not propelled by any air pressure differential. It simply coasts in a drag-free airless tube after an initial acceleration. For bearings, think mag lev without propulsion.
First, got to build the tube to withstand 4kg/cm2 pressure (at about 100 feet deep) and be rigid enough to withstand wave action flexing so as to maintain tight mag-lev tolerances. Got to keep the tube in place - either with multi propellors with gps feedback or bouys in opposition with deep sea anchors.
Next, got to evacuate some 7.7 million cu meters of air. Next, capsule has to provide fresh air at atmosphere pressure for passenger comfort. Got a problem? Need escape hatches periodically which must have vacuum locks to admit you to 100 ft sea depth for prompt medical attention.
And last, this thing has to have automatic terrorist detection and annihilation.
I'm recommending everyone purchase a share in this, just to get the bridge that surely must come with it.

How about trying this idea out in a tunnel under theland firs? Like from New York to Chicago to Los Angeles, etc.It may be easier to achieve this than under the water. Going under the ocean may be tried out later.

For sure there're challenges with vacuum maglev -- especially the current unavailability of room temperature superconductors AFAIK..
but the prospect of using very little energy per trip is appealing :)

Interestingly enough Elon Musk gave a Fireside chat a few nights ago in which he mentions that he is about to reveal a fifth mode of transportation which he calls the hyperloop. See here, http://new.livestream.com/pandodaily/elonmusk/videos/1908918
It's suppose to be crash proof, immune to weather and solar powered. He envisions travel at twice the speed of an airliner with travel times of under 30 minutes between LA and San Francisco. He agreed when asked that it's like a Jetson's tunnel. However his tweet of July 15th says he will publish something in four weeks and that it is “not a vac tunnel”.

"It is hard to imagine anything worse than to be stuck thousands of miles away from land, under the ocean, in a vacuum tube."
"Maybe falling from the sky packed in a tube with other passengers and jet fuel might be worse but we risk that too"
Yes, but we understand the risks of flying (they are pretty low). And we have methods of rescue if things go wrong. What are the risks of this high speed tube? Is there any way of rescuing if the device gets stuck somehow? Or does everyone die? Lots of people died in the first attempts at flight. This is highly experimental. In fact, has anything of the sort (even a few miles long) been built? Build a working test unit and maybe people might be more likely to put some money behind the idea.